The present invention relates to a plasma display for use in thin TVs, personal computers, workstations and the like, and the plasma display operation.
In recent years, color plasma displays (PDP) provided with a memory function have been in demand for the purpose of making thin displays that can replace color CRTs that are widely used in television receivers. There are two kinds of plasma displays provided with a memory function, i.e. an AC type and a DC type. The DC type PDP, which is considered more practical, is explained below with reference to FIGS. 2 and 3.
As illustrated in FIG. 2, a DC type plasma display has two kinds of display matrix groups, i.e. a scan electrode group 4 consisting of cathodes K1, K2, K3, etc. and a display electrode group 5 consisting of anodes A1, A2, A3, etc. with each respective crossing point thereof forming a display discharge cell 3. A space between display electrode group 5 and scan electrode group 4 is filled with a discharge gas such as helium-xenon or the like. The discharge cell, 3 formed where a display electrode and a scan electrode cross each other, emits discharge light upon application of a voltage according to display information. The light emitted by the numerous discharge cells 3 results visual information which is recognizable by a viewer. For color displays, a quartet structure formed of two green pixels, one blue pixel and one red pixel is used and fluorescent substances corresponding to the above colors are disposed on each respective discharge cell 3.
Next, producing the intensities of the pixels in the picture display will be explained.
FIG. 3 is a time chart illustrating how the intensities are produced. One field corresponding to a picture is divided into a plurality of sub-fields, and the intensities are produced by controlling the light emission period of each respective sub-field. In this particular case, the number of intensity levels is 2.sup.8 =256. One field is divided into 8 sub-fields, each having an equal time period, and the light emission period of each respective sub-field is assigned a different value. Pixels on each respective scan line can be displayed in any of the 256 intensity levels by selecting the light emission period at the corresponding sub-fields.
Accordingly, color image display is made possible with a plasma display by forming discharge cells 3 at the crossing points between display electrodes and scan electrodes. Phosphors of green, blue and red are disposed in a quartet structure and illuminated to create a color display. Varying the intensity of the display is made possible by means of the sub-fields.
The arrangement of two green pixels disposed in the quartet structure enhances brightness and also improves the apparent display resolution. Since there are two green pixels in the quartet structure, simply supplying video signals to respective pixels of red, green and blue would disturb the white balance and reproduce excessive green color. On the other hand, supplying the green video signal with its amplitude reduced by 1/2 in order to preserve the white balance would cause the intensity to deteriorate to 128 levels due to a reduction in the signal amplitude.